1. Field of the Invention
The present invention relates to a method of manufacturing a strip of unvulcanized rubber compound with short fibers mixed therein, more particularly to a method of orienting short fibers towards at least two directions.
2. Description of the Related Art
In a pneumatic tire called studless tire, in order to increase the frictional coefficient on the ice-covered road surface, the use of tread rubber including short fibers oriented in the radial direction of the tire has been proposed. In the laid-open Japanese patent application JP-A-2001-130228, such a tire is disclosed, wherein the tread rubber is, as shown in FIG. 7, made by accordion-folding a very thin sheet (a) of unvulcanized rubber with short fibers oriented towards the normal direction to the folding direction. In this case, almost all of the short fibers (f) are oriented in one direction, namely, the tire radial direction, therefore, the frictional coefficient is efficiently increased. But, it is difficult to make use of the short fibers for the propose of reinforcing the tread rubber. If short fibers are oriented towards the tire circumferential direction, the tread rubber may be reinforced.